I'm in my mid forties and I've been working for pay in tech since '96, so this puts me in a similar demographic like yours.
I think you're being too picky and greatly limiting your job choices. I miss the days of private offices, but those days are over in any moderately cutting edge companies. You'll find offices in Cisco, Juniper and Oracle, you'll find open seating at Google, Facebook, and startups. WFH friendly companies generally expect you to become productive before they're ok with fill time WFH. As a senior engineer, you are expected to mentor junior engineers and participate in broad design and architecture, that's much harder to do from home. Unlike you, I have kids, which puts severe constraints on my time, and I find myself WFH quite a bit, but my company is ok with it, since I'm productive. Open offices suck, I agree, but find a coping mechanism - for me it's a noise canceling headset, a pile of music on my phone, and a very careful arrangement of whiteboards to pretend I have some privacy. I'm not doing anything strange at work, just the activity around me is distracting. It's sad, but for the time being, private offices are extinct.
As a senior engineer, you also spend more time in meetings - precisely because that's how you disseminate knowledge to other people in a corporate environment.
If you've been working for a while, you probably have deep expertise in some area, find companies which need that and are willing to pay for it. No strange startups with low salary and high equity, etc. I don't know about you, but over my career, I've made hundreds of professional connections. It's difficult to walk in the front door with grey hair for a fair interview, since in our field, people view us older folks as has-beens. Call in those former connections.
Anyhow, good luck! Try not to get stuck being too curmudgeonly.